The present invention relates to a high-voltage circuit breaker having at least two circuit-breaker poles, in particular having three poles, each circuit-breaker pole having at least one interrupter unit whose actuatable switching contact can be actuated by a joint actuating mechanism via a switching rod so that in the event of a closing operation there is a time delay at least between the closing of the interrupter units of two circuit-breaker poles. At least the switching rod of a first circuit-breaker pole being is connected to the actuating mechanism via a lever.
A high-voltage circuit breaker is described in, for example, German Patent No. 195 24 636. As described therein, the actuatable switching contacts of the interrupter units are actuated by a joint actuating mechanism via switching rods. The actuatable switching contact of the interrupter unit of a first circuit-breaker pole is connected to an actuating shaft directly via the switching rod and a lever, and the actuatable switching contacts of the second and third circuit-breaker poles are actuated by actuating shafts assigned to these circuit-breaker poles. These actuating shafts are connected to the actuating shaft that can be actuated by the actuating mechanism.
In order to achieve a time delay between the closing of the interrupter unit of one circuit-breaker pole and that of the next, the levers that are connected to one another via the connector rods and the lever that is rigidly attached to the actuating shaft assigned to the first circuit-breaker pole have actuating lever arms of unequal length. Furthermore, these levers are not arranged parallel to one another but rather are arranged at an angle adapted to one another. Because the interrupter units are closed subject to a time delay, it is possible, for example, to switch capacitor banks into the circuit when the phase voltage in question passes through zero or to switch transformers into the circuit when the phase voltage in question reaches a maximum. However, it is disadvantageous that this is achieved by providing a plurality of levers of different lengths. In addition, arranging them on the actuating shafts involves considerable expense, because each lever has to be arranged at a different angle relative to the actuating shafts. Nonetheless, in the case of this high-voltage circuit breaker, the interrupter units are opened subject to a time delay between one circuit-breaker pole and the next.
An object of the present invention is to create provide a high-voltage circuit breaker which allows assembly costs and the number of components to be reduced and in which, in the event of a closing operation, the interrupter unit of one circuit-breaker pole closes subject to a time delay or the interrupter units close subject to a time delay between one circuit-breaker pole and the next.
According to the present invention, this is achieved in that only the switching rod of the second and/or third circuit-breaker pole is connected to the actuating mechanism via spring elements that are compressible in the event of a closing operation and expand after contact has been made.
According to an advantageous embodiment the respective spring elements are arranged in a recess of a sleeve and are delimited by a shoulder of the recess and by the shoulder of a collar of a coupling rod that extends into the recess or of a switching rod.
According to an example refinement of the present invention, the sleeve that holds the spring elements has a bearing via which it is connected to a lever that is rigidly attached to the actuating shaft, and the coupling rod that extends into the recess of the sleeve has a second bearing via which it is connected to a lever that is rigidly attached to a second actuating shaft, the second actuating shaft being connected to the switching rod assigned to the interrupter unit of the second circuit-breaker pole.
If a first sleeve of this kind is assigned to only one circuit-breaker pole of a three-pole high-voltage circuit breaker, ungrounded capacitor banks can be optimally connected into the circuit. This means the jump-like increase in the voltage of the third phase that occurs in the case of synchronous closing can be avoided, because the interrupter unit of the circuit-breaker pole to which the spring elements are assigned closes subject to a time delay. The switching rods of the other two circuit-breaker poles are directly connected via levers to the actuating shaft that can be actuated by the actuating mechanism.
In the case of a synchronous closing operation in a three-pole high-voltage circuit breaker, the substantial dielectric and mechanical load on a device connected in a three-phase system can be reduced in that the interrupter units are closed subject to a time delay between one circuit-breaker pole and the next, so that the interrupter units are closed as the current wave passes through zero.
To accomplish this, according to a further embodiment of the present invention, a second sleeve which holds the spring elements in a recess and which on one side is indirectly and rigidly attached to the first sleeve via a coupling rod that extends into the recess, the first sleeve being connected to the actuating shaft via the bearing and the lever, and on the other side is connected via a bearing to a lever that is rigidly attached to a third actuating shaft that is connected to the switching rod assigned to the interrupter unit of the third circuit-breaker pole, is arranged axially downstream from the first sleeve.
As the switching rods of two circuit-breaker poles are connected to the actuating mechanism via spring elements that are compressible in the event of a closing operation, the spring elements have different spring deflections and/or different spring characteristics in order to ensure that the interrupter units are closed subject to a time delay from one circuit-breaker pole to the next. If spring elements having different spring characteristics are used, the spring elements having the least stiff spring characteristic are assigned to the switching rod of the circuit-breaker pole having the longest time delay in the event of a closing operation. Cup springs may be used as the spring elements.
If compressible spring elements are assigned to a second and third circuit-breaker pole, the coupling rod that extends into the recess of the second sleeve is rigidly connected to the first sleeve, which is connected to the actuating shaft via a bearing; because of this, inside the recess of the second sleeve the spring elements are delimited on one side by a shoulder of a collar of the associated coupling rod. On the front end of the sleeve, on the opposite side from the shoulder of the collar of the coupling rod, the deflection of the spring elements is delimited by a stop element. As a result, in the event of a closing procedure, in which the coupling rod of the second sleeve functions as a pull rod, the spring elements in both sleeves are compressed.
In the event of a switching operation, to ensure the switching movement caused by the actuating mechanism is transferred, a further lever is rigidly attached to the second and third actuating shafts, respectively. These levers are connected to the switching rods of the second and third circuit-breaker poles.
Given that in the event of a closing operation the compressible spring elements expand after contact has been made, when an opening operation is initiated the sleeves can be immediately carried along by the lever that is rigidly attached to the actuating shaft without any time delay. This is accomplished in that when the opening operation is initiated, the sleeve is carried along due to the fact that the collar of the coupling rod rests against a stop element at the front end of the sleeve opposite the shoulder of the recess.
The desired functioning of the present invention can also be achieved if the sleeve that holds the spring elements is integrated into the switching rod of the second and/or third circuit-breaker pole.
Sleeves may also be assigned in this way in the case of one circuit-breaker pole or two circuit-breaker poles of a three-pole high-voltage circuit breaker.